The present invention relates to a powder inhaler.
One of the present lines of development in pharmaceutical research is pulmonary administration of medication in the form of a dry powder. The lungs constitute a path for easy interchange between inhaled air and the blood, thereby making it possible for an inhaled substance to pass substantially instantaneously into the blood. The effect of the substance is thus quicker than when the same substance is administered via the digestion or by intramuscular injection. In addition, by comparison with an intravenous injection, which also has very rapid effects, inhalation is much easier to use and gives rise to fewer secondary effects.
Pharmaceuticals already exist in dry powder form, generally mixed with excipients. In contrast, the present invention relates to substances in powder form that are very pure and that are not mixed with excipients, thereby avoiding the secondary effects of excipients. As a result, the quantity of substance to be inhaled is very small, generally of the order of 0.2 mg to 5 mg. Furthermore, such substances must be inhaled in doses that are very accurate: ideally, inhaled dose error should be less than 5% by mass.
Devices enabling medication to be inhaled in powder form already exist in the state of the art: however, the accuracy of the dose inhaled using such devices is of the order of 5 mg: such devices are not suitable. Document FR-A-2 334 424 discloses a propellent gas inhaler that is heavy since it is made at least in part of metal, and its operating life is limited by the supply of propellent gas. The placing of a dose of substance to be inhaled is not very practical, and its mechanism is fragile and delicate.